Version 5 (modified by Martin Dix, 14 months ago) (diff)


I've done a one year CABLE run starting from a Jan 1 initial state from the au-aa655 CABLE AMIP run and compared to a similar one year JULES run also starting from an AMIP initial state.

My CABLE run is basically a copy of Jhan's u-ap748 with a couple of tweaks to the reconfiguration to enable it to work with the AMIP file.

Time series of various global means at (log in with your NCI account).

Maps of annual mean differences attached. NetCDF files with the monthly data are /short/p66/mrd599/ (JULES) and (CABLE).

In the annual mean the TOA net flux is 1.2 W/m2 with JULES and -2.3 with CABLE, consistent with the cooling.

Net heat flux in bare soil regions is about 5 W/m2 in CABLE, even though the depth averaged soil temperature doesn't change much over the year.

To further investigate the surface energy balance I set up JULES and CABLE versions of the single column model, suites u-ar806 and u-ar807 respectively.

Used a configuration with bare soil, zero initial soil moisture and relaxation to initial atmospheric state to allow long runs with an extreme diurnal cycle.

In routine stempv, added a calculation of the integrated soil heat content and the initial and corrected ground heat flux.

   ! Integrated heat content
   tmp = 0.
   DO k = 1, ms
      tmp(:) = tmp(:) + ssnow%tgg(:,k)*ssnow%gammzz(:,k)
   write(6,*) "COLUMN HEAT", tmp
   write(6,*) "DT", ssnow%tgg(:,1) - tgg_save(:)
   write(6,*) "GA", canopy%ga, canopy%dgdtg, canopy%ga + canopy%dgdtg*(ssnow%tgg(:,1) - tgg_save(:))

This can be compared with the net surface heat flux calculated from the SCM diagnostics surfsw + surf_lw - sens_ht - lat_ht.

The old access 1.3 version of the SCM doesn't have quite the same options for atmospheric relaxation but it's possible to set up a case that has a similarly large diurnal cycle and soil warming. The original 7.3 case used a 30 minute time step and 3 hourly radiation. Changed to 20 minutes and hourly radiation to better match other cases

Averaged over the last 40 days of the runs

JULES 10.6 CABLE 10.6 CABLE 7.3 CABLE 7.3 hourly
SCM net 4.41 10.87 6.77 6.81
Soil change 4.36 5.18 6.51 6.55
GA 5.87 8.69 5.69 6.11
GA corrected 5.22 6.51 6.56

In access 1.3 there was a good agreement between the SCM net flux and the soil temperature change with the higher frequency radiation making almost no difference. In 10.6 CABLE seems to be losing about 5 W/m2.

The UM has a net radiation on tiles diagnostic that was not saved by the SCM for some reason so I added it. In both JULES and CABLE this uses the updated surface temperature to calculate the upward LW, so should better match the soil temperature change. CABLE 7.3 results from here on are using hourly radiation.

Grid box net radiation 95.14 73.19 33.60
Tile net radiation 95.12 67.45 33.26
Tile net flux 4.40 5.13 6.47
Soil change 4.36 5.18 6.55

Therefore it seems that using the radnet_tile diagnostic the energy balance is equally good in JULES and CABLE. However this isn't the flux that the atmosphere uses. Neither JULES nor CABLE alter the grid box mean LW which is what affects the atmosphere.

Following plots are the mean diurnal cycle over the last 40 days of the runs

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